To predict by selecting the outcome that is most representative of the input.

To predict by selecting the outcome that is most representative of the input.

• A. Illusion of validity
• B. Representativeness bias
• C. Overconfidence bias
• D. Base rate neglect

Answer: (A)

Illusion of validity is the tendency to overestimate how accurate your prediction is after seeing a small, seemingly representative input. When you predict by selecting the outcome that looks most like the input, you’re trusting a pattern you perceive and assume it will generalize. That creates a confident, but unwarranted, sense of accuracy even if the evidence is weak or the sample isn’t truly representative. This differs from simply applying a representativeness heuristic, which is about judging probabilities based on similarity to a prototype; here the focus is the inflated certainty about the prediction itself. Overconfidence plays a role, but the mechanism described—believing the prediction is valid because the input seems representative—fits Illusion of validity.

Illusion of validity is the tendency to overestimate how accurate your prediction is after seeing a small, seemingly representative input. When you predict by selecting the outcome that looks most like the input, you’re trusting a pattern you perceive and assume it will generalize. That creates a confident, but unwarranted, sense of accuracy even if the evidence is weak or the sample isn’t truly representative. This differs from simply applying a representativeness heuristic, which is about judging probabilities based on similarity to a prototype; here the focus is the inflated certainty about the prediction itself. Overconfidence plays a role, but the mechanism described—believing the prediction is valid because the input seems representative—fits Illusion of validity.